Many important nearshore fisheries in northern California rely on healthy kelp forests, either as a food source or important habitat. These fisheries are threatened because of a dramatic decline of the state’s kelp forests north of San Francisco. Aerial surveys of the kelp in 2008 and 2014 by the California Department of Fish and Wildlife (CDFW), revealed a 93% decline of canopy-forming kelp species in this region (you can view the CDFW aerial kelp surveys in the CeNCOOS Data portal [linked...]).

Two consecutive years of warm water conditions and unprecedented numbers of purple urchins on the north coast have contributed to the lack of kelp in 2014 and 2015. Subsurface temperatures (at 30-feet) in the kelp forests in Mendocino County hit a record high in the Fall of 2014, and saw comparable temperatures in 2015. These spikes in temperature were caused by the “Warm Blob” in 2014, coupled with the strong El Niño conditions in 2015. Warm water, and diminished nutrients associated with warm water, stresses the kelp and makes it more vulnerable to urchin grazing.

Cal Poly Assistant Professor Ryan Walter discusses impacts of prolonged warm water on seagrass in central California and local efforts to assess marine ecosystem changes. This year’s El Niño is among the strongest ever recorded. Combined with the “warm blob” persisting throughout the northeast Pacific Ocean, the last two years have...